修改默认alert弹框样式

<script>

window.alert = function(msg, callback) {
var div = document.createElement("div");
div.innerHTML = "<style type=\"text/css\">"
		+ ".nbaMask { position: fixed; z-index: 1000; top: 0; right: 0; left: 0; bottom: 0; background: rgba(0, 0, 0, 0.5); }                                                                                                                                                                       "
		+ ".nbaMaskTransparent { position: fixed; z-index: 1000; top: 0; right: 0; left: 0; bottom: 0; }                                                                                                                                                                                            "
		+ ".nbaDialog { position: fixed; z-index: 5000; width: 80%; max-width: 300px; top: 50%; left: 50%; -webkit-transform: translate(-50%, -50%); transform: translate(-50%, -50%); background-color: #fff; text-align: center; border-radius: 8px; overflow: hidden; opacity: 1; color: white; }"
		+ ".nbaDialog .nbaDialogHd { padding: .2rem .27rem .08rem .27rem; }                                                                                                                                                                                                                         "
		+ ".nbaDialog .nbaDialogHd .nbaDialogTitle { font-size: 17px; font-weight: 400; }                                                                                                                                                                                                           "
		+ ".nbaDialog .nbaDialogBd { padding: 0 .27rem; font-size: 15px; line-height: 1.3; word-wrap: break-word; word-break: break-all; color: #000000; }                                                                                                                                          "
		+ ".nbaDialog .nbaDialogFt { position: relative; line-height: 48px; font-size: 17px; display: -webkit-box; display: -webkit-flex; display: flex; }                                                                                                                                          "
		+ ".nbaDialog .nbaDialogFt:after { content: \" \"; position: absolute; left: 0; top: 0; right: 0; height: 1px; border-top: 1px solid #e6e6e6; color: #e6e6e6; -webkit-transform-origin: 0 0; transform-origin: 0 0; -webkit-transform: scaleY(0.5); transform: scaleY(0.5); }               "
		+ ".nbaDialog .nbaDialogBtn { display: block; -webkit-box-flex: 1; -webkit-flex: 1; flex: 1; color: #09BB07; text-decoration: none; -webkit-tap-highlight-color: transparent; position: relative; margin-bottom: 0; }                                                                       "
		+ ".nbaDialog .nbaDialogBtn:after { content: \" \"; position: absolute; left: 0; top: 0; width: 1px; bottom: 0; border-left: 1px solid #e6e6e6; color: #e6e6e6; -webkit-transform-origin: 0 0; transform-origin: 0 0; -webkit-transform: scaleX(0.5); transform: scaleX(0.5); }             "
		+ ".nbaDialog a { text-decoration: none; -webkit-tap-highlight-color: transparent; }"
		+ "</style>"
		+ "<div id=\"dialogs2\" style=\"display: none\">"
		+ "<div class=\"nbaMask\"></div>"
		+ "<div class=\"nbaDialog\">"
		+ "	<div class=\"nbaDialogHd\">"
		+ "		<strong class=\"nbaDialogTitle\"></strong>"
		+ "	</div>"
		+ "	<div class=\"nbaDialogBd\" id=\"dialog_msg2\">弹窗内容，告知当前状态、信息和解决方法，描述文字尽量控制在三行内</div>"
		+ "	<div class=\"nbaDialogHd\">"
		+ "		<strong class=\"nbaDialogTitle\"></strong>"
		+ "	</div>"
		+ "	<div class=\"nbaDialogFt\">"
		+ "		<a href=\"javascript:;\" class=\"nbaDialogBtn nbaDialogBtnPrimary\" id=\"dialog_ok2\">确定</a>"
		+ "	</div></div></div>";
document.body.appendChild(div);

var dialogs2 = document.getElementById("dialogs2");
dialogs2.style.display = 'block';

var dialog_msg2 = document.getElementById("dialog_msg2");
dialog_msg2.innerHTML = msg;

// var dialog_cancel = document.getElementById("dialog_cancel");
// dialog_cancel.onclick = function() {
// dialogs2.style.display = 'none';
// };
var dialog_ok2 = document.getElementById("dialog_ok2");
dialog_ok2.onclick = function() {
	dialogs2.style.display = 'none';
	//callback();  //这是回调函数！
};
};
alert("哈哈哈！！！看，没有标题~_~");
</script>